Legal claims defining the scope of protection, as filed with the USPTO.
1. A carrier frequency offset (CFO) tracking loop module, comprising: a numerically-controlled oscillator (NCO) that calculates an NCO phase output; a CFO phase error block that generates a corrected NCO phase output by subtracting half of a residual CFO phase error from the NCO phase output; a pilot processor that generates a phase error by averaging phases of pilot subcarriers; a multiplier that corrects the pilot subcarrier's phase by multiplying complex values of the pilot subcarriers with a conjugated complex value of the corrected NCO phase output; and a loop filter that filters the phase error from the pilot processor and updates the NCO with the filtered phase error.
2. The module of claim 1 , wherein a CFO phase error is estimated using a long sequence, the channel estimation sequence, and the pilot subcarriers, and wherein the residual CFO phase error is estimated using a channel estimation sequence and before a frame synchronization is performed.
3. The module of claim 1 , further comprising an equalizer that performs channel estimation by removal of a CFO phase error before other estimation steps.
4. The module of claim 1 , further comprising an equalizer that de-rotates channel estimation coefficients based on the residual CFO phase error.
6. The module of claim 1 , further comprising a plurality of subcarriers; wherein a first subcarrier having a higher Signal to Noise Ratio (SNR) than a second subcarrier is nominated to be a pilot subcarrier.
7. The module of claim 6 , wherein a transmit data of the first subcarrier is obtained at a receiver via a slicer operation.
8. The module of claim 1 , wherein the residual CFO phase error is estimated from two channel estimation symbols.
9. A method, comprising: calculating a phase output; estimating a residual carrier frequency offset (CFO) phase error using a channel estimation sequence; performing a frame synchronization after estimating the residual CFO phase error; generating a phase error by averaging a plurality of phases of a plurality of pilot subcarriers; generating a corrected phase output by subtracting half of the residual CFO phase error from the phase output; correcting the phase of the pilot subcarriers by multiplying a plurality of complex values of the pilot subcarriers by a conjugated complex value of the corrected phase output; filtering the phase error from the pilot processor; and updating a numerically-controlled oscillator (NCO) with the filtered phase error.
10. The method of claim 9 , wherein the phase error is estimated using a long sequence, the channel estimation sequence and the pilot sub carriers.
11. The method of claim 9 , further comprising performing channel estimation by removal of the phase error before other estimation steps such that the subtracting is not performed.
12. The method of claim 9 , further comprising de-rotating channel estimation coefficients based on the phase error such that the subtracting is not performed.
14. The method of claim 9 , further comprising nominating a first subcarrier having higher a Signal to Noise Ratio (SNR) than a second subcarrier to be a pilot subcarrier.
15. The method of claim 14 , further comprising slicing, at a receiver, the first subcarrier to generate a transmit data.
16. The method of claim 9 , wherein the residual CFO phase error is estimated from two channel estimation symbols.
Unknown
February 25, 2014
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